As the world's population increases, consumer demand for electrical energy also increases. Fossil fuels (e.g., coal, oil, and natural gas) have been used as an energy source in electrical power plants for many years. Burning fossil fuels generates air pollutants such as carbon dioxide. These emissions may have a negative effect on the environment and may contribute to climate change. Further, to reduce air pollutants, some countries have passed laws that limit allowable air pollutants. These laws generally increase the cost of generating electrical energy from fossil fuels. Fossil fuel deposits around the world are being depleted because they are not being replenished at a rate commensurate with consumption. Access to fossil fuels is also often dependent on world political and economic conditions. These factors combine to cause increasing and unstable prices for energy generated from fossil fuels.
One solution to the problems of pollution from energy production via fossil fuels, diminishing fossil fuel deposits, increasing fossil fuel prices, fossil fuel price volatility, and government regulation is to use other energy sources, such as renewable energy sources, to generate electrical energy. Renewable energy sources such as wind, solar (e.g., photovoltaic), and geothermal are now available on a commercial basis, and the cost of electricity produced using these methods is generally decreasing as they become more prevalent and the underlying technologies are refined. Renewable energy sources thus provide potential solutions to the cost, availability, and environmental concerns associated with use of fossil fuels for electrical energy production.
One drawback associated with renewable energy sources is that their energy production may be affected by factors beyond the control of any operator such as darkness, lack of wind, or weather. For example, the sun does not shine all day every day, and the wind does not blow steadily all day every day. Therefore, solar cells and wind turbines cannot produce a steady energy output all day every day. However, it is desirable to achieve a relatively steady power output from these energy sources. Conversely, energy sources powered by fossil fuels such as gas turbine generators have a peak efficiency achieved at an output level determined by the design of the generator such that it is desirable to operate the generator at a specific output level associated with peak efficiency. However, as described above, energy demand may vary significantly. In each of these scenarios, a system for augmenting power provided by the energy source to the load is desirable.